1. Field of the Invention
The present invention relates to a stopper for a small diameter blood collection tube and, more particularly, relates to a stopper for a blood collection tube having an internal diameter that is no larger than about 0.250".
2. Background Description
Blood collection tubes are commonly used by a doctor, phlebotomist or nurse to draw a sample of body fluid from a patient in a hospital or doctor's office for diagnostic testing. Generally the blood collection tube contains a vacuum that aids in drawing the body fluid from a puncture wound in the patient into the tube. For example, an evacuated blood collection tube is commonly used with a double-ended needle, wherein one end of the needle is inserted into the patient's arm and the other end is used to pierce through a stopper on the open end of the tube. When the needle enters the evacuated tube a predetermined amount of blood is drawn from the patient into the tube based upon the amount of vacuum in the tube. As vacuum in the tube increases, greater amounts of body fluid can be drawn into the tube. Because of the importance of retaining the predetermined amount of vacuum in the tube during shipping and storage of the tube, it is important that the stopper on the tube fits securely over the open end of the tube and maintains the vacuum in the tube.
It is also important that the vacuum level is maintained in the tube to draw the desired volume of blood into the tube to limit any discomfort to the patient. Since the patient has one end of the needle in the skin during the drawing operation, the patient may experience pain during the operation which can be minimized by performing the operation as quickly as possible. If the vacuum in the tube is deficient, however, subsequent removal of the tube and insertion of another tube would be necessary which would prolong the unpleasant procedure.
As those skilled in the field of blood collection are aware, the use of smaller diameter tubes for collecting small volumes of blood is becoming more desirable. In particular, tubes having an internal diameter of no greater than about 0.250" are preferred for some types of blood collection. Therefore, there is an ever increasing need for a stopper for these small diameter tubes that is capable of maintaining a predetermined vacuum within the tube. In addition, because of the small diameter opening in these tubes there is a problem with directing the needle through the stopper and into the small opening in the tube. Currently, a special adapter must be mounted on top of the stopper to align the tube during needle insertion.